Non-rotating drill pipe protectors are disclosed in several US patents held by Western Well Tool, Inc. (WWT), including U.S. Pat. No. 5,069,297; U.S. Pat. No. 5,803,193; U.S. Pat. No. 6,250,405; U.S. Pat. No. 6,378,633; U.S. Pat. No. 6,739,415; and U.S. Pat. No. 7,005,631. Each of these patent publications is incorporated herein in their entirety by this reference. These several patents describe a non-rotating drill pipe protector consisting of a stop collar and sleeve. The stop collar and sleeve are hinged to allow assembly onto drill pipe in the field.
Also described in the patents listed are numerous design features that allow increased performance in torque reduction, drag reductions, improved wear resistance, resistance to being moved on the drill pipe, and improved flow-by characteristics. These patents also describe structures that produce a “fluid bearing” function between the non-rotating drill pipe protector sleeve and the drill pipe.
The performance characteristics described in the WWT patents are reflected in the incorporation of specialty materials such as (1) rubber for a sleeve liner to improve the fluid bearing and hence the torque reduction of the drill pipe, and (2) ultra high molecular weight polyethylene for wear and sliding pads to reduce friction between the stop collar and sleeve and of the sleeve to the casing. Special materials such as aluminum are used in the stop collars to facilitate a flexible structure that can grip a variety of pipe diameters. Specially formulated urethanes are used in the sleeve body to provide resistance to a variety of downhole fluids. Specialty steel reinforcement is used to provide a long fatigue dependent operational life.
These performance characteristics are also reflected in the particular shape of the assembly, especially the drill pipe protector sleeves. The sleeves have external recessed areas that allow flow past the sleeve to be less restricted (reduced Effective Circulating Density, ECD). Shape is important on the ends of the sleeves to have channels to allow fluid to escape from the sleeve and lubricate the interface of the sleeve to the stop collar. The shape of the sleeve is also important to facilitate sliding on the low friction pads, and hence, in one embodiment, the sleeve profile is made of multiple large diameter arcs.
Most recently, ProBond (International), Ltd., Aberdeen, U.K. has disclosed a wear protector method and apparatus in US Patent Publication No. US 2006/0196036 ('036) that describes wear protectors both as rotating and non-rotating. These wear protectors are of various configurations that are formed by injection of a composite molding material directly into removable molds on the drill pipe. In addition, UK Patent GB 2,388,390 ('390) describes strips of ceramic material attached to a cage-like structure that is hinged. The '036 and '390 references are incorporated herein in their entirety by this reference.
A purpose of the present invention is to expand the potential use of an injection molded non-rotating drill pipe protector to incorporate numerous additional features that are available with hinged non-rotating drill pipe protectors. All special features would also be applicable to rotating drill pipe protectors and to casing centralizers.